Welcome! Today we'll explore what lies beneath our feet. Earth is not just a solid ball of rock. Instead, it has a complex layered structure, much like an onion. From the thin crust we live on to the incredibly hot core at the center, each layer has unique properties and plays a crucial role in making our planet what it is.
The crust is Earth's outermost layer and the one we live on. It's incredibly thin compared to the rest of the planet - imagine the skin of an apple compared to the whole fruit. There are two types of crust: continental crust, which forms our continents and is 20 to 70 kilometers thick, and oceanic crust, which lies beneath the oceans and is only 5 to 10 kilometers thick. The crust is made of solid rock and contains all the mountains, valleys, and ocean floors we see.
The mantle is Earth's largest layer by volume, making up about 84 percent of our planet. It extends from just below the crust down to about 2900 kilometers deep. Despite being mostly solid rock, the mantle behaves like a very thick, slow-moving fluid due to the extreme heat and pressure. Temperatures in the mantle range from 500 degrees Celsius near the top to over 4000 degrees Celsius near the core. This heat causes convection currents - hot rock rises while cooler rock sinks, creating a slow circulation that drives plate tectonics on Earth's surface.
The core is Earth's innermost layer and consists of two parts. The outer core is liquid iron and nickel, extending from about 2900 to 5100 kilometers deep. The inner core is solid iron and nickel, from 5100 kilometers to the center at 6371 kilometers deep. Temperatures in the core reach an incredible 5000 to 6000 degrees Celsius - as hot as the surface of the Sun! The movement of liquid iron in the outer core generates electric currents, which create Earth's magnetic field that protects us from harmful solar radiation.
To summarize, Earth consists of four main layers. The crust is our thin outer shell, only 5 to 70 kilometers thick, where we live. The mantle extends 2900 kilometers deep and drives plate tectonics through convection. The outer core is 2200 kilometers of liquid metal that generates our magnetic field. Finally, the inner core is a solid metal ball 1220 kilometers in radius at the very center. Each layer has unique properties and temperatures, working together to create the dynamic planet we call home. Understanding Earth's internal structure helps us appreciate the complex processes that make life on our planet possible.